Locking mechanism for electric switches



Nov. 20, 1945. J. M. ANDERSON 2,389,400

LOCKING MECHANISM FOR ELECTRIC SWITCHES Filed June 50, 1942 5Sheets-Sheet 1 Irwvemtor: James P! .,-Ander*son,

His Attorney.

Nov. 20, 1945.

Filed June 30, 1942 J. M. ANDERSON LOCKING MECHANISM FOR ELECTRICSWITCHES 5 Sheets-Sheet 2 Inventor:

Ja mes M Anderson,

I! i E Attorney.

Nov. 20, 1945.

J. M. ANDERSON 2,389,400

LOCKING MECHANISM FOR ELECTRIC SWITCHES Filed June 50, 1942 5Sheets-Sheet 3 Inventor: James M.Ander-sorw,

y His Attorney Nov. 20, 1945. J. M. ANDERSON 2,389,400

LOCKING MECHANISM FOR ELECTRIC SWITCHES Filed June 30, 1942 5Sheets-Sheet 4 Inventor:

James M Anderson,

|s Att orrwey.

Nov. 20, 1945. J. M. ANDERSON 2,339,400

LOCKING MECHANISM FOR ELECTRIC SWITCHES Filed June 30, 1942 5Sheets-Sheet s Inverwtor: James M. Amderson,

by )V M Kin/M1444 His Attorney.

Patented Nov. 20, 1945 LOCKING MECHANISM FOR ELECTRIC SWITCHES James M.Anderson, Broomall, Pa., assignor to General Electric Company, acorporation of New York Application June 30, 1942, Serial No. 449,060

16 Claims.

My invention relates to improvements in looking mechanisms for electricswitches and more particularly for trip-free circuit breakers whichoperate automatically in response to abnormal circuit conditions tointerrupt a circuit and whose operation, under certain emergencies, mustbe prevented even during the existence of an abnormal circuit conditionand, also, in consequence oi shocks, vibrations, and the like.

In certain applications of automatic circuit breakers, crucial momentsarise when it becomes absolutely necessary that the circuit breakersremain closed, especially under shocks, and often even though operatingunder the abnormal circult conditions which would normally require acircuit opening operation. Sometimes, it is equally important to preventan undesired circuit closing operation in consequence of shocks, as wellas heedless closing on the part of the operator. Also, at times, it mustbe possible to close a circult breaker under abnormal circuit conditionsand keep it closed. I1 abnormal circuit conditions occur while a circuitbreaker is locked against opening, then the locking action must be suchthat the circuit breaker mechanism cannot be released to a point wherethe circuit breaker could open slowly on subsequent release of thelocking action. For convenience and simplicity of operation, it isdesirable to have a single operating member by which all looking and andtripping functions can be performed and pa -cularly without requiringthe continued presence or the op erator. It is also important to have adependable indicating means which will readily show the stage of thelocking action,

operated to lock an electric switch, and especially an automatic circuitbreaker, in the open circuit position so that it cannot be closed eitherheedlessly or by shock. A still "further object of my invention is toprovide a locking means which can be applied to circuit breakerspreviously installed and still in service. Also, an object of myinvention is to provide a locking and tripping mechanism in which allthe functions of locking and manual tripping can be accomplished by themanipulation of one operating member and without any necessity for thecontinued presence of the operator to maintain the locking features.Also, a further object of my invention is to provide means forpositively indicating the-stage of the locking action. These and otherobjects of my invention will appear in more detail herein after.

In accordance with my invention, I provide for an electric switch, andparticularly an automatic circuit breaker, a locking mechanismcomprising an operating member which can be moved in one directionthrough a plurality of positions to lock the switch in the closedcircuit position against automatic tripping and, also, against openingdue to shock and to lock the switch in the open circuit position againstheedless closing or by. shock. all without requiring the continuedpresence of the operator. Also, in accordance with my invention, Iprovide a locking mechanism which in the locking positions does notpermit enough An object of my invention is to provide means adapted tobe operated to lock an electric switch, and especially an automaticcircuit breaker, in the closed circuit position so that it cannot openin consequence of abnormal circuit conditions or because of shock, orboth. Another object of my pe'oially an automatic circuit breaker, inthe closed circuit position so that upon release of the looking actionthe switch will not open slowly in the event that abnormal circuitconditions occurred while the switch was locked. A further object of myinvention is to provide means adapted to be movement of the switch partsin consequence of shock or attempts at automatic tripping while theswitch is closed to permit a slow opening of the switch mechanism whenthe locking action is released by a reverse movement of thelockoperating member. Further in accordance with my invention, I providea locking mechanism in which another predetermined movement of theoperating member will effect the opening of the switch when the lockingactions are released. Also, in accordance with my invention, I providean indicating means responsive to the movement of the operating memberthrough its plurality of positions for positively indicating eachlocking action.

My invention will be better understood from the following descriptionwhen considered in connection with the accompanying five sheets ofdrawings, and its scope will be pointed out in" the ppended claims. Inthe accompanying drawings, Fig. l illuse trates in perspective anautomatic circuit breaker and locking mechanism embodying myinventionvthe locking mechanism being spaced from ping and shock; Fig. 5is a view similar to Fig. 2 7

showing the circuit breaker locked in the open position; Fig. 6 is aview similar to Fig. 5 showing a modification of my invention forlocking the circuit breaker in the open position; Fig. 7 is a sideelevation partly in section of another circuit breaker mechanism and amodification of the embodiment of my invention shown in Fig- 1 with thecircuit breaker closed and the locking mechanism in the normal orunlocked position; Fig. 8 is a part sectional-view 'on'the line 8-6 ofFig. 7 ;-Fig. 9' is a view' similar to Fig. 7 showing the circuitbreaker closed and the locking mechanism-in the trip locked position;Fig. 10 is a view similar to Fig. 7 showing the circuit breaker closedand locked against opening byboth tripping and by shock; Fig. 11 is aside elevation partly in section of stillanother circuit breakermechanism and a'modification of the embodiment of my invention shown inFig. 1 with the circuit breaker closed and the locking mechanism in thenormal or unlocked position; Fig. 12 is a view similar to Fig, 11showing the circuit breaker 'open and trip locked forclosing; Fig. 13 isa view similar to Fig. 11 showing the circuit breaker closed and lockedagainst opening by both tripping and shock; and Fig. 14 illustrates inperspective one element of the locking mechanism shown in Figs. 11, 12and 13.

In Figs. 1' to 5, inclusive, I have illustrated an embodiment of myinvention as applied to a latched closed type of automatic circuitbreaker l5, shown more completely'i'n Fig. '12 This particular circuitbreaker is disclosed in United States Letters Patent 2,227,160 and, asshown herein, comprises two suitably mounted contact blocks l6 and H,which are arranged to be bridged by a movable contact l8. 'This contactis suitably mounted on a carrying arm 19, which is pivotally supportedon a stationary pin in the circuit breaker frame '20. The arm !9 alsocarries an arcing contact 2|, which cooperates with a stationary arcingcontact 22 on the upper contact block IT. The movable arcing contact 2|is connected to the'lower stud hiby a flexible conductor 23.

, 'For controlling the movement of the contact carrying arm iii to andfrom the closed circuit position, the circuitbr'eaker is'provicled withan operating mechanism of the mechanical advantage typ comprising a maintoggle having links 24 pivotally connected tothe arm 19 by a'pin 25 andlinks 26 supported on a stationary pivot pin2'l and pivotally joinedwith the links" 24 by a pin 28; a secondary toggle having links 29supported on the pin 28 and connected by a pin 30 to links 3| which are"pivotally supported on a movable abutment pin-32; and an operatingtoggle comprising links 32' and 33' respectively supported on the pins21 and 3D 'and'pivotally interconnected at 34. When the circuit breakerhas more than one pole, the several poles are interconneoted'by acrossbar 35 which, as shown, is suitably secured toan angular extension36 of the links 26. As long as the abutment pin 3 2 is held in theposition shown in Fig. l, the toggles 24-26, 29-3l, and 32'-33 aremaintained in the position shown in Fig. 1 by a latch 31 pivotallysupported on the pin 26 and suitably biased by force of gravity, aspring or both, for rotation in a direction to engage the pin 39intermediate the elements of the link 33.

For holding'the abutment pin 32 in the positaining the pin 32stationary, the links 40 and 7 4| form an-underset toggle which isrestrained in a thrust transmitting position by a latching mem-' berpivotally supported at 41 and biased to latching position by a spring,not shown. In order more firmly to hold this member 46 in the latchingposition in ordinary use, there is provided a secondary latching member48 which engages the tail 49 of the latch 45 to prevent rotation thereofin the latch releasing direction. The secondary latch 48 is mounted on ashaft 5%) and biased to latching position by a spring, not shown. Thislatch is caused to rotate in the latch releasing direction, When it isdesired to trip the circuit breaker, by suitable electroresponsivemeans,- illustrated as an electromagnetic tripping device 5|. This, asis well known to the art, may be connected to be responsive to the cur-'rent flowing through the particular pole of circuit breaker. In ordermore positively to effect the release of the main latch 46, the tall 48"of the secondary latch 48 is arranged on movement in the trippingdirection, to hit the tail 49 of the main latch. Since, in general, in amultiple-pole breaker, it is desirable to open all poles in the event ofan abnormal condition prevailing on one or more, the secondary trippinglatch 48 of the mechanism pole is arranged to be actuated in response tothe operation of the tripping device 5| associated with the respectivepoles. For this purpose, there'is provided'for a pole adjacent themechanism pole a trip shaft to be'rotated by the tripping device 5|.This shaft is not shown in the drawings, but as disclosed in Uni-tedStates Letters Patent 2,141,272,-it' engages slots 15 in a rotatablymounted member 52 which is rigidly associated with the latch 48. Theseveral members are so coupled that the actuation'of any tripping device5| actuates'the member 52 and thereby causes the release of the latchingmembers 46 and 48 and the dropping of the abut ment pins 32 to effectthe collapse of the toggle mechanism of each pole of the circuitbreaker.

For resetting the collapsible mechanism which holds the abutment pin 32and actuating the tog gle mechanism to close the circuit breaker whenthe abutment pin 32 is'held stationary; there is mounted-on a. suitablysupported shaft 54 an operating handle 55 for actuating a crank pin 56,the movement of which is imparted to the toggle link 32 and the rest ofthe mechanism through links 51 which are connected to the links-32' by auni versal joint 58; When the circuit breaker is open, the mechanism'maybe reset for closing by turning the operating handle 55in one directionand the circuit breaker closed by turning" the handle in the oppositedirection.

For locking the circuit breaker closed to prevent tripping electrically,needlessly, or by shock; locking the toggle mechanism to prevent openingneedlessly or by shock; locking the circuit breaker open to preventclosing either heedlessly or by shock; and also for tripping the circuitbreaker, I provide a locking and tripping mechanism 66, shown moreclearly in Fig. 1 and for the sake of clearness, displaced to the leftof the circuit breaker l5. As illustrated, this mechanism 60 comprises arotatably and reciprocably mounted, manually operable member 6|, movablefrom an initial and normal position shown in Figs. 1 and 2' to anotherposition shown in Fig. 3 to prevent the release of the circuit breakerholding means comprising the trip latch 48; to a third position shown inFig. 4 to prevent circuit opening movement of the contact l6; and to aposition shown in Fig. intermediate said initial and third positions toprevent a circuit closing operation while the contact I8 is in the opencircuit position, said member being longitudinally movable in onedirection while in the initial position to effect the release of thecircuit breaker holding means.

In order to effect the recited locking operations,

the rotatable member or shaft 6|, which has an operating handle 62, isjournaled at its inner end in two bushings 63 mounted in a generallyU-shaped support 64. As shown the outer end of the shaft 6| and also thecircuit breaker operating shaft 54 may project through openings in aswitchboard 64' of the dead-front metallic type. Bending stresses on theshaft 6| may be relieved to some extent by supporting the handle 62 in abracket 62' secured to the switchboard 64'.

Splined on the shaft 6| within the support 64 so as to rotate with theshaft 6| and yet permit a limited longitudinal movement thereof underthe bias of a spring 59 is a threaded cylindrical member 65, cooperatingwith a traveling nut 66. To guide this nut and prevent it from turning,a guide rod 61 journaled in the support 64 is provided. In order toutilize the movement of the nut 66 for the various locking purposes, itis arranged to actuate an arm 68 for blocking move ment of the rotatabletrip member 52 and the latch 48 rigidly associated therewith as shown inFigs. 3, 4 and 5 and also to actuate a blocking lever 69 mounted on astationary pivot 10 for blocking the pin 28 in the circuit closedposition shown in Fig. 4 and in the circuit open position shown in Fig.5. The arm 68 is mounted at an intermediate point on links H whichconnect the nut 66 to the blocking lever 69 so as to impart motionthereto.

Cooperating with the blocking arm 68 for looking the circuit breakeragainst tripping is a crank 12, which is suitably secured to a shaft 13.This shaft is suitably coupled to or interlocked with the trip member 52as by the tongue 14 and slot 15 arrangement illustrated in Fig. 1 and issuitably supported at its outer end in a bearing bracket 13 secured tothe frame 64. For blocking purposes, the crank 12 is provided with aninclined, shouldered portion I6 over which the blocking arm 68 is movedfrom the unlocked position shown in Figs. 1 and 2 to the trip lockedposition shown in Fig. 3 and then to the locked position shown in Fig. 4when the operating handle 62 is turned clockwise, as viewed in Fig. 1,to effect travel of the nut 66 from right to left. As this nut travelsto the locked position, a hook-shaped portion 11 on the blocking lever69 engages a roller 18 on the toggle joint pin 28 whereby to lock thispin against transitory movement.

For best results, it is not sufficient merely to lock the pin 26 in theposition shown in Fig. 1 since under these conditions all the forcenecessary to maintain the circuit breaker closed is transmitted to thelatching mechanism. Consequently, if, while the circuit breaker isclosed. there were any tendency for opening, the parts might so settlethat the latching mechanism could not hold the circuit breaker closed.Therefore, a subsequent release of the locking mechanism would result ina slow opening of the circuit breaker. This could be most dangerous notonly to the operator but also to the apparatus, especially if thecircuit breaker opened under heavy load or fault currents. In order toavoid this possibility, I provide the hook H of the blocking lever 69with a shouldered portion 19 such that as the lever 69 is moved to thelocking position, the toggle joint pin 28 is raised from the positionshown in Figs. 1, 2, and 3 to the position shown in Fig. 4 just enoughto take the load oif the latching mechanism and thus leave this free tosettle to the fully latched position in case it has been deranged byshock or otherwise while the circuit breaker was locked. Incidentally,this raising of the toggle joint pin 28 materiall straightens the togglecomprising the links 24 and 26 so that this toggle is in a better thrusttransmitting position when the circuit breaker is locked than otherwise.

In order to trip the circuit breaker by pulling outwardly on the handle62 when the locking mechanism is in the normal or unlocked position, thetripping crank 12 is provided with a wing portion through a hole inwhich the inner end of the shaft 6| projects. On this inner end of theshaft, there is suitably secured a projection 8i, engageable with thewing 80 of the tripping crank 12 to turn this crank in the trippingdirection when the handle 62 is pulled outwardly. In order more rigidlto hold the tripping crank 12 against possible tripping when the lockingmechanism is in the locked position shown in Fig. 4, the inner end 61'of the nut guide rod 61 may be arranged to abut a wing 82 on thetripping crank 12, as shown more clearly in Fig. 4.

' In order to know the position of the locking mechanism when thecircuit breaker is closed without'the necessity of examination of theparts, I provide a visual indicating mechanism 83, shown in Figs. 1 and2. As illustrated, this mechanism comprises a gear member 84 which isrotatably mounted in a supporting plate 84' and which is adapted to beturned upon rotation of the shaft Bl by a fractional gear 85 mounted onthe shaft 6|. I use the fractional gear 85 since the number of turns ofthe shaft 6| to effect movement of the nut 66 from one locking positionto the other would impart too much movement to the gear 84 for thepurpose I have in mind. In one embodiment of my invention, I mold thefractional gear 85 into an insulation coupling 86 having a molded-inmetallic bushing 81 whereby it is joined to an extension of the shaft 6|so as to provide insulation and safet for the operator. On the gear 84,I mount a plurality of indicating vanes respectively marked unlocked,"trip locked, and locked. These are visible when turned into the uppervertical position through a window 68 in the switchboard 64', theswitchboard leg of the bracket 62 on dead-front switchboards, and abacking plate. For definitel setting or clocking the gear 84 as it ismoved tooth by tooth, I provide a spring pressed pawl 89.

Inasmuch as it is sometimes just as important to prevent an open circuitbreaker from being closed by shock as it is to prevent a, closed circuitbreaker from beingopened b shock, I provide in conjunction with thelocking means described for maintaining the circuit breaker closed, anar rangement for also holding it open, as shown in Figs. 1 to 5,inclusive. This is accomplished by providing the blocking lever 69 witha notch 90, which in the open position of the circuit breaker is adaptedto be operated by movement of the lock operating handle 62 to a positionto embrace the roller 18 on the toggle joint pin 28 whereby to preventthe straightening of the toggle comprising the links 25 and 26, as shownin Fig. 5. I have found out that if the blocking lever 69 does not havethis full semicircular opening 90, but is shaped as shown in Fig. 6, thebreaker can also be effectively prevented from closing by turning on theoperating handle 62 in the locking direction until the locking lever 69of Fig. 6 engages the roller I8. This latter arrangement apparently iseffective in consequence of the cramping of the parts due to the factthat there is more or less lost motion in consequence of the necessaryclearances and manufacturing tolerances. However, I prefer thearrangement shown in Figs. 1 to since this insures a more eflicient andpositive way of locking the toggle pin 28 in the open circuit position.

In order that the locking mechanism 60 may be quickly and easilyattached to and detached from the circuit breaker, the U-shaped frame 64is arranged to be bolted directl to the circuit breaker frame 20 at 9|and 92, as shown more clearly in Figs. 2 to 6, inclusive. Also, as shownin Fig. 2, the indicating mechanism 83 and its mounting plate 84' may besupported integrally with the locking mechanism 60, by a bracket 93 ofinsulating material suitably secured to the U- shaped frame 64 as, forexample by an angle support 94.

Assuming the parts positioned as shown in Figs. 1 and 2, then thecircuit breaker is unlocked and can function normally as an automatictripfree circuit breaker since neither the trip latch 48 nor the toggle24, 26 is restrained against movement. If it is desired to lock thecircuit breaker against being tripped automatically, heedlessly or byshock, then the operating handle 62 is turned clockwise, as viewed inFig. 1, until the trip locked vane appears in the window 88. The nut 66is then in the position shown in Fig. 3 with the arm 68 bearing on theshoulder 16 of the crank I2 whereby to lock this crank against movementand thus to prevent any tripping action of the trip latch 48. If, whilethe circuit breaker is closed and the locking mechanism is unlocked, asshown in Figs. 1 and 2, the circuit breaker is automatically opened inresponse to the actuation of the electroresponsive device 5| and it isdesired to reclose the breaker even though the circuit controlled by thebreaker may be faulty or heavily overloaded, then the operator afterresetting the circuit breaker mechanism turns the handle 62 clockwisefrom the unlocked position to the trip locked position. The trip latch48 is then locked against movement and the circuit breaker can be closedon overload or fault currents. In other words, whenever the circuitbreaker opens, it ispossible to reclose it and be sure that it willremain closed by first resetting the circuit breaker mechanism, thenmoving the locking mechanism to the trip locked position, and finallyclosing the circuit breaker.

In the event "that it is desired to prevent the opening of the circuitbreaker by shock which might release the circuit breaker mechanismholding latch 31, then the operating handle is turned clockwise untilthe locked indicator vane appears in the window 88 and the parts assumethe position shown in Fig. 4 with the hookshaped portion of theoperating lever tilengaging the roller I8 on the toggle joint pin 28.During this movement of the operating handle 62 to the locked position,the shoulder 19 on the hook-shaped portion of the operating lever 69raises the toggle joint pin 28 sufiiciently to take the load of thecircuit breaker toggle mechanism off the abutment 32 and the collapsiblelatching mechanism associated therewith, as previously described, sothat this mechanism can settleinto normal position in the event that thelatches are jarred loose while the circuit breaker is closed and lockedagainst shock. Then, when the locking mechanism is released, the breakermechanism is correctly latched so as to prevent a slow opening of thecircuit breaker and'the dangers consequent upon drawing arcs. If thecircuit breaker is open and it is desired to lock it from closingagainst shock or heedless action,

then the locking handle 62 is turned clockwise until the arc-shapedportion til engages the roller E8 on the togglejoint pin 28, as shown inFig. 5. It is then impossible to reclose the circuit breaker. 1 V o InFigs. '7, 8, 9, and 10, I have illustrated an embodiment of my inventionas applied to an automatic trip-free circuit breaker .mechanism such asdisclosed in United States Letters Pat'- ent 2,152,453, issued March 28,1939.. As shown; this mechanism comprises a main operating tog-. gleconsisting of links it and NH pivotally joined at I02. This toggle isarranged to be actuated by a rotatably mounted handle I93, the rota tionof which turns a crank I54 to move a reciprocably guided crosshead I65.This is connected to the crank pin of the crank I36 by a link I06 and tothe toggle joint pin I02 by a link IIl'I. The toggle link Iilll ispivotally connected by a pin I88 to a link I09 mounted on a stationarypivot III]. The toggle link IGI is pivotally connected by a pin III to acrank In, which is rotatable on a fixed shaft II3.

The crank '2 has two rigidly interconnected, parallel wings H4 and H5through which the shaft IIB extends. The wing Il lisconnectedto thetoggle link IIII, while the Wing I I5 is provided with a cam surfaceHi5. This cam surface is arranged to coact with a contact-operatingcrank III, which is rigidly connected through a rotatable suitablyinsulated countershaft II8 to the movable contact carrying arm H9 of thecircuit breaker. When the crank I52 is rotated clockwise bystraightening the operating toggle ItIi-IE!I in response to elevation ofthe crosshead I05, the cam face He bearing on a roller I20 on the crankI I1 rotates the countershaft I Hi counterclockwise to bring the movablecontact structure I2I of the circuit breaker into engagement with thestationary contact structure I22, I23.

In order to hold thetoggle IfilIL-Iti at the pivot I08 in thrusttransmitting position relative 1y to the crank H2, there is associatedwith the toggle guide link I09 a latching and tripping means comprisinga link I24; which is connected to the pin I08 and to a latch I25 mountedon a fixed 'pivot I264 The link I24 and the latch I25 are suitablyinterconnected, as at I21, to insure a force reducing connection.Coacting aaeaaoo with the latch I25 is a rotatable tripping shaft I28 towhich is secured a detent member I29 adapted to engage the tail of thelatch I30.

In the position shown, collapse of the toggle I-IN, that is,counterclockwise rotation of the pivot pin I08 and tripping of thetoggle joint I02, is restrained by the latch I and the detent I29.Tripping movement, that is, counterclockwise rotation of the trippingshaft I28, effects release of the latch I25 so that it is free to rotatecounterclockwise to release the pin I08 and thereby permit collapse ofthe toggle. In the circuit closed position, the toggle I00--IOI is heldin an underset position by a prop I3l which is arranged to support thetoggle joint I02. This prop is secured to a rotatable shaft I32 and isresiliently connected by a spring I33 to an arm on the tripping shaftI28 so as to facilitate resetting of both the prop and the latchingmeans after a circuit opening operation of the mechanism. The prop I3Iis also biased for counterclockwise rotation by suitable means, such asa torsion spring I 34.

The tripping shaft I28 is provided with an arm I35 whereby it can berotated counterclockwise to the releasing position by suitableelectroresponsive means, indicated simply as the end of the trippingplunger I36 of an electromagnet which may be energized, for xample, inresponse to the current flowing through the circuit breaker, as is wellknown to the art. Clockwise rotation of the tripping shaft is limited bya sto I35.

The contact operating crank II! is connected to the crank II2 by meansof a compression spring I31, which is guided on a member I38 engagingone end of the crank H2 and having a guided sliding connection at I39with the downwardly extending arm of the crank III. In the closedcircuit position shown, the spring I3! is under compression so thatimmediately upon release of the tripping latch, the collapse of thetoggle I00-I 0| is accelerated by'the energy stored in the springwhereby to effect rapid movement oi the cam surface IIB away from theroller I20.

The contact operating crank Ill is also acted upon throughout theopening movement by the spring I31, tending to accelerate separation ofthe contacts I2I, I22, and I23. During the closing operation when thecrank H2 is rotated clockwise, the spring I31 is placed undercompression by reason of the comparatively long 1e- Ver arm of the crankIII acting in opposition to the spring. V

When the toggle I00-IOI is released in response to a tripping operation,the pivot pin I08 is free to rotate counterclockwise about pivot I I0.This causes a shift of the toggle joint I02 from the end of the prop I3Iand permits a free collapse of the toggle. When this occurs, the pivotI00 reverses its movement and drops so that the latch I25 can return toits initial position. During this return movement, the nose I of thelatch rides over the latch detent I 29 and resets in the positionillustrated in Fig. 1. The prop I3I is suitably shaped, as illustrated,for permitting free movement of the toggle joint I 02 alongside theprop.

The resilient connection I33 between the trip shaft I28 and the prop I3Ibiasing the tripping detent into latching engagement after the latchI25, in dropping, pushes down on and passes by the latch detent I29, thelatter snapping into reset position due to the bias of the spring I 33.At the same time, the spring I33 and the spring I34 exert acounterclockwise bias on the prop I 3| urging it against the side oflink I01 so that when thelinks I00 and ID! are raised to theposition,shown in Fig. '7, in a subsequent closing operation, the propI3I is snapped beneath the toggle joint I02 to hold the mechanism in theclosed position independently of the actuating handle I03. A stop memberI40 is provided for preventing movement of the prop beyond the togglejoint I02.

As in the embodiment of. my invention shown in Fig. l, I have providedmeans for locking the circuit breaker against opening in case of a shockwhich would release the latching mechanism or the prop I3I and also incase of automatic tripping and needless tripping. The locking mechanismcomprises a rotatable shaft 6 I which is journaled at its inner end intwo bushings 63' mounted in a generally U-shaped support 60'. The shaftSI will, of course, be provided with a suitable operating handle andindicating mechanism, which may be like that shown in Fig. 1. Splined onthe inner end of the shaft GI within the support 64' so as to rotatewith the shaft and yet permit a limited longitudinal movement thereof,is a threaded cylindrical member 65' coopcrating with a traveling nut66. In this case, the nut 86' is guided and prevented from turning byone side of theU-shaped member 64' and a supporting plate 64", which issuitably secured to a portion 20" of the circuit breaker frame. In orderto utilize the movement of the nut 66' for the various locking purposes,it is provided with a projection II, which extends inwardly toward thecircuit breaker mechanism and also carries a stifiiy spring-biasedplunger 68.

When the parts are positioned, as in Fig. 7, for the normal intendedoperation of the circuit breaker, the nut 66' is substantially againstthe side of the inner leg of the U-shaped member 64' with the plunger 60clear of the shoulder I25 of the latch I25 so that this latch is free tobe released whenever the tripping shaft I 23 is actuated. If it isdesired to prevent any release of the circuit breaker mechanism byactuation of the latch I25, the shaft 61 is turned in the directionindicated by the arrow at in Fig. 7 until the plunger 68 rides under theend of the shoulder I25 on the latch I 25 into the position shown inFig. 9. The circuit breaker latching mechanism cannot then be tripped byshock or other wise since the latch I25 is preventedfrom rotatingcounterclockwise, that is in the tripping direction. Preferably, I soarrange the plunger 63' that it actually rotates the latch I25 clockwiseenough to clear the detent I29 on the tripping shaft I28 in order thatthis shaft may be free to return to the normal non-trip position inwhichthe detent I20 would engage the nose I30 of the latch. If this is notdone, there is a likelihood that, because of lost motion due tomanufacturing tolerances, the latch I25 might move clockwise enough toprevent the restoration of-the detent I29 to hold the latch when theplunger stop 68 is backed oil to the position shown in Fig. 1. Thiscould result in an undesired and dangerous opening of the circuitbreaker.

If it is desired to prevent release of the prop I3I by shock, then theshaft BI is turned further in the direction indicated by the arrow (1 tothe position shown in Fig. 10 with the nut 66' at the outer end of itstravel. In this case, the projection 1|, carried by the nut 63', movesover a projection or shelf I 3 I' on the inner end of the prop I3I toprevent any possibility of clockwise rotation of the prop and release ofthe opcrating toggle l -'-|0l by reason of the removal of the support ofthe toggle joint pin I02. Thus, with the parts positioned, as shown inFig. 2', the circuit breaker operating toggle'is locked against releaseby shock and the latching mechanism is alsolocked against release byshock, automatic tripping, and headless operation.

For tripping the circuit breaker manually, the tripping shaft I28 islengthwise movably mounted and is provided with a projection I28, whichextends'in the path of-movement of a projection 8lmounted-onthe shaft 6|so as to partake only of the lengthwise movement thereof. Thus, if it isdesired to trip the circuit breaker manually, the shaft BI is pulledoutwardly in the direction-indicated by the arrow b against the bias ofareturn spring 99' and a return spring I00 until the projection 8| on-theshaft 6| engages the-projection |28"on the tripping shaft I28 and movesthis shaft sufficiently to release the detent 129" from the latch 125.If the locking mechanismis in the trip locked or shock locked positionandthe operating shaft BI is pulled outwardly, the tripping shaft willbe actuated to the releasing position, but the circuit breaker will notopen; Moreover, if the handle is subsequently released; the trippingshaft can return to the latching position because of the oversetcondition of'the latch I25 when'the plunger 68' lies under the shoulderI25 of the latch.

In Figs. ll, 12, and 13, I'haveillustrated an embodiment of my'inventionas applied to another form of automatic trip-free circuit breakermechanism known to the art. This mechanism is for controlling theopening and closing movements of a contact carrying arm 200, which ismounted on a stationary pivot 20!. Thi arm carries an arcing contact 202and alsoa suitable main contact of the bridging type, which is notillustrated,- since its specific structure constitutes no part of mypresent invention. The movable arcing contact 202 cooperates with astationary arcing contact 203.; The operating mechanism comprises ato'gglelever 204, which is mounted on a stationary pivot 205 andprovided on one 'side of this pivot with a crossbar 206 for connectingthe mechanisms of the several poles of a 'multi-pole circuit breaker. Onthe-other side of the pivot 205, an arm of the toggle lever 204 isfconnected" to the contact carrying arm 200 through a toggle comprisinglinks 201 and 208, pivotally connected at209, and respectively pivotedto the contact carrying arm 200 at 210 and the toggle lever-204 at 2|I.' The toggle joint pin 209 is constrained to move in a circular are by'a link '2l2 mounted on a stationary-pivot 2l3. The links 20'Iand 2l2joined at 209 constitute a toggle for controlling the movement of thecontact arm 20*0.

For trip-free operation of the circuit breaker, there is provided anoperating lever 214, which is mounted on the stationary pivot 205, andreadily releasable means for rigidly connecting the operating lever tothe toggle lever 204'. This means comprises a prop latch 2 l 5, which ispivotally supported on the toggle lever at 216. This prop latch isarranged to engage a roller 2H,

a compression spring 219, shown in Fig.11, but omitted in the otherfigures for the sake of clearness. This spring is interposed between thelong tail 228 of the secondary latch and a shoulder-on the prop latch.-When the circuit breaker is open and the parts positioned as shown inFig. 12 with the latches 2|5 and 2I9 correctly engaged with each otherand the latch 2| 5 in engagement with the roller 2H, clockwise movementof the operating lever 2l4 moves the contact carrying arm 200 into thecircuit closing position where it is held by a hook latch 220, which ismounted on which is mounted on a pin 2"; carried by the operating leverH4. The prop-latch 215 is maintained ,in the latching position by asecondary j'latch 2l9, which is mounted on the pivot 21! in the togglelever 204. The prop and secondary latches are biased for clockwisemovement into latching engagement with each other and the prop latchinto engagement with the roller 2!! by a stationary pivot 22l and whichis engaged by the pin 2l8 on the operating lever to maintain the circuitbreaker closed. The latch 220 is biased for counterclockwise movement byaftorsion spring, not shown. This movement is limited by a projection220 on the latch which engages amember 225' mounted on the pivot 20!.During the opening of the circuit breaker, a small clockwise movement ofthe latch 220 is effected when the pin 2H engages the upper edge of thelatch, as shown in Fig. 12. r The latching mechanism is released foropening the circuit breaker by an impulse tripping device, whichcomprises a, tripping lever 222 mounted on the stationary pivot 22l andbiased for counterclockwise rotation by a compression spring 223, theleft-hand abutment of which is omitted. As shown more clearly inFig-"ll, the tripping latch 222 is maintained in the biased position bya tripping catch 224 mounted on the pivot 20| and restrained againstclockwise rotation by suitable bias, including the weight ofa trippingarmature, not shown. Rigidly associated with the tripping catch 224 isan arm 225" to which is secured a tripping crossbar 226, Thisinterconnects with similar arms associated with the other poles of amulti-pole circuit breaker so that the actuation of the arm 225 in anypole by the associated tripping magnet of that pole or otherwise willeffect releasing or clockwise rotation of the catch 224. When thisoccurs and the spring 223 causes clockwise rotation of the trippinglever 222, an arm 22! thereof is pushed against the long arm 228 of thesecondary latch 219 to rotate it counterclockwise and free its short armfrom the prop latch 2l5 and to cause the long arm of the secondary latchto hit the prop latch and free it from the roller 2H. The weight of thecircuit breaker parts and contacts, strongly biased by compressionsprings, not illustrated, and the bias of a compression spring 229,which is energized during the closing of the circuit breaker, effects aquick circuit opening movement of the contact arm2 00. During theopening movement, the counterclockwsie rotation of the toggle lever 204is utilized to release the hook latch 220 from'the pin 2 [8. This isaccomplished by having a'projection 0n the toggle lever 204 such as thepin 2| I, for example, engage the upper edge of the hook latch androtate the same clockwise out of engagement with the pin 2I8. I

To reset the circuit breaker mechanism for closing, the closing lever214 is turned counterclockwise about its pivot 205 from the lowerposition shown in Fig. 11 to the upper position shown in Fig. 12. Duringthis movement, a projection 230 on the closing lever 2l4 engages a tail23l on the latch 222 and rotates this latch counterclockwise about itspivot 22! until the roller on the tripping arm 224 drops into latchingposition with the latch 222. Atthe same time, the impulse trippingspring 223 is reenergized. As soon as the projection 22! of the latch222 is moved clear of the tail 228 of the secondary latch 2H1, thislatch and the prop latch are free to reset under the bias of spring 2l9'into latching engagement with each other and the prop latch intoengagement with the roller 2". The toggle lever 204 and the closinglever 2 are then again rigidly interlatched, as shown in Fig. 12.Downward clockwise movement of the operating lever 2l4 closes thecircuit breaker and brings the pin 2| 8 into engagement with the hooklatch 220.

As in the other illustrated embodiments of my invention, I have providedmeans for locking the circuit breaker against opening in case of ashock, which would release the latches that hold the contact arm 200 inthe circuit closing position and, also, in case of automatic trippingand heedless tripping. The locking mechanism comprises a rotatable shaft61', which is journaled at its inner end in two bearings 63" arranged tobe suitably secured to the circuit breaker frame. The shaft 5| will, ofcourse, be provided with a suitable operating handle and indicatingmechanism, which may be like that shown in Fig. l. Splined on the innerend of the shaft 6 l' between the support 63" so as to rotate with theshaft and yet permit a limited longitudinal movement thereof is athreaded cylindrical member 65 cooperating with a traveling nut 66',which is suitably guided and prevented from turning when the cylindricalmember 65' is actuated by turning the shaft 6| When the parts arepositioned as shown in Fig. 11 for the normal, intended operation of thecircuit breaker, the nut 66" is substantially against the inner bearingmember 63".

For utilizing the travel of the nut 66' to perform the desired lockingoperations, I provide, as shown more clearly in Fig. 14, a blockingmember 232 which, particularly for circuit breakers already installed,may consist of two separate elements 233 and 234 respectively, suitablyjoined as by a crossbar 235 and cap screws 236, For assembly on aninstalled circuit breaker, the elements 233 and 234 of this blockingmember are separately mounted on opposite ends of the pivot 205 and thenjoined by the crossbar 235. The element 233 is connected by a link 23'!to the nut 66' to partake of movement thereof.

For the normal, intended operation of the circuit breaker, the blockingmember 232 is in the position shown in Fig. 11, and in this position, itis ineffective to prevent opening of the circuit breaker from any cause.If it is desired to lock the circuit breaker closed against shock andtripping, then the shaft BI is turned in the direction indicated by thearrow a to advance the nut 66 to the position shown in Fig. 13. In sodoing, the blocking member is rotated counterclockwise about its axis205 to the full blocking position. In this position, the inner end ofthe lefthand prop 234 abuts squarely against an arm 238, which isrigidly associated with the tripping arm 224 whereby to prevent anyclockwise rotation of this arm to the tripping position. At the sametime, an adjustable abutment, such as a screw Nil-mounted on theleft-hand blocking member 234, engages the hook latch 220 to lock thsame against release by shock from the pin 2H3. The circuit breakermechanism is further blocked against movement by projections 240 and 24!respectively mounted on the leftand right-hand prop members and sopositioned that, as shown in Fig. 13, the members 240 and 2 respectivelycome under rollers 242 mounted on the leftand right-hand ends of thetoggle joint pin 209.

The members 240 and 2 thus hold the toggle joint pin 209 to prevent anopening movement of the contact arm 200. Further to insure that the proplatch 215 and secondary latch 2|! are maintained in the correct latchingposition so that the circuit breaker will not open when the blockingmember 232 is released, I provide on this member an adjustable abutment243, which engages the short tail of the secondary latch 2|! to preventcounterclockwise rotation and release of this latch from the prop latch2l5. In other words, all of the latches and toggle features are soblocked that regardless of shock and attempts at tripping, eitherautomatic or otherwise, the circuit breaker cannot be opened.

Referring now to Fig. 12 in which the circuit breaker mechanism is shownin the open position and reset ready to close, the blocking mem her 232has been partially rotated around its axis 2G5 so that the prop member234 is down in front of the trip arm extension 238 to effectively blockany clockwise movement of the trip am 224 to the tripping position.Consequently, the circuit breaker can now be closed on an overload andwill remain closed. Then, when closed, the shaft 0! can be rotated toturn the blocking member 232 to the full locked position shown in Fig.13 so as completely to lock the circuit breaker against automatictripping, heedless tripping, and shock.

As in the other modifications of my locking mechanism, the shaft BI isreciprocably mounted so that it can be moved in the direction of thearrow b to trip the circuit breaker. The shaft 6| is biased for movementin the direction opposite to the arrow b by a spring 99. For trippingthe circuit breaker upon movement of the shaft 6| in the direction ofthe arrow b, this movement is arranged to be imparted to the trippingbar 226 through a motion transmitting mechanism comprising a crank 244,a connecting rod 245, and a crank arm 246 on the tripping bar. The crank244 is pivoted on a stationary pivot 241 and loosely pivoted to theshaft 6| at 248.

7 The connecting rod 245 is preferably adjustable,

as shown. With this arrangement, it will be obvious that when the shaft6! is moved in the direction of the arrow 11, the connecting rod 245 ismoved upwardly to turn the tripping am 224 to the circuit breakerreleasing position whereby to effect the opening of the circuit breaker.If the blocking mechanism is in either the fully locked position shownin Fig. 13 or the intermediate trip locked position shown in Fig. 12,then the circuit breaker cannot be heedlessly tripped by pullingoutwardly on the shaft GI. Hence, the tripping arm 224 is then blockedagainst clockwise rotation.

While I have shown and described my invention in considerable detail, Ido not desire to be limited to the exact arrangements shown, but seek tocover in the appended claims all those modifications that fall withinthe true spirit and scope of my invention.

What I claim as new and desire to secure by Letter Patent of the UnitedStates is:

1. In a locking mechanism for an electric switch having relativelymovable cooperating contacts provided with actuating means for efiectinga circuit closing movement thereof together with means for holding thecontacts in the circuit closing position and means for releasing theholding means; locking means movable from an initial position to anotherposition to prevent the release of the holding means and to a thirdposition to prevent relative movement of the contacts, and a rotatablemember for efiecting the movement of said locking means longitudinallymovable in one direction while the locking means is in the initialposition to effect the release of the holding means.

2. In a locking mechanism fOr an electric switch having relativelymovable cooperating contacts provided with actuating means for effectinga circuit closing movement thereof together with means fo holding thecontacts in the circuit closing position, and means for releasing theholding means; locking means movable from an initial position to anotherposition to prevent the release of the holding means and to a thirdposition to prevent relative movement of the contacts while in thecircuit closing position and to a position intermediate said initial andthird positions to prevent a circuit closing operation of the contactswhile in the circuit open position.

3. In a locking mechanism for an electric switch having relativelymovable cooperating contacts provided with actuating means for eifectinga circuit closing movement thereof together with means for holding thecontacts in the circuit closing position, and means for releasing theholding means; locking means movable from an initial position to anotherposition to prevent the release of the holding means and to a thirdposition to prevent relative movement of the contacts while in thecircuit closing position and to a position intermediate said initial andthird positions to prevent a circuit closing operaton of the contactswhile in the circuit open position, and a rotatable member for efiectingthe movement of said locking means longitudinally movable in onedirection while the locking means is in the initial position to effectthe release of the holding means. 7

4. In a locking mechanism'for an automatic electric circuit breakerhaving a relatively stationary contact, a cooperating pivotallysupported contact, a toggle mechanism for moving the cooperating contactinto current-conducting engagement with the stationary contact, alatching member for holding the toggle mechanism in a thrusttransmitting position to maintain the contacts in circuit closingposition, and electroresponsive means for releasing the latching member;locking means movable from an initial position to another position toprevent movement of the latching member from the toggle holding positionand to a third position to hold the toggle mechanism in a thrusttransmitting position in-- dependently of the holding means, wherebyv tomaintain the contactsin the circuit closing position and to a positionintermediate said initial and third positions to prevent a circuitclosing operation of the contacts while in the circuit open position. I

5. In a locking device for an automatic electric circuit breaker havinga relatively stationary contact, a cooperating pivotally supportedcontact, a toggle mechanism for moving the cooperating contact intocurrent-conducting engagement with the stationary contact, a latchingmember for holding the toggle mechanism in a thrust trans mittingposition to maintain the contacts in circuit closing position, andelectroresponsive means for releasing the latching member; locking meansmovable from an initial position to another position to prevent movementof the latching memher from the'toggle holding position and to a thirdposition to hold the toggle mechanism in a thrust'transmitting positionindependently of the holding means whereby to maintain the contacts inthe circuit closing position, said locking means comprising areciprocably mounted member biased for movement in one direction andadapted to be moved in the opposite direction while the locking means isin the initial position to effect the release of said latching member.

6. In a locking mechanism for an automatic electric circuit breakerhaving a relatively stationary contact, a cooperating pivotallysupported contact, a toggle mechanism for moving the cooperating contactinto current-conducting engagement with the stationary contact, apivoted latching member for holding the toggle mechanism in apredetermined thrust transmitting position to maintain the contacts incircuit closing position, and electroresponsive means for releasing thelatching member; locking means movable from an initial position toanother position to prevent turning of the latching member from thetoggle holding position andto a third position to hold the togglemechanism ina different predetermined thrust transmitting positionindependently of the holding means whereby to maintain the contacts inthe circuit closing position, said locking means comprising areciprocably mounted member biased for movement in one direction andadapted to be'moved in the opposite direction while the locking means isin the initial position to efieot the release of said latching member.-I

'7. In a locking mechanism for an automatic electric circuit breakerhaving relatively fixed and movable cooperating contacts, a togglemechanism for moving the movable contact into ourrent-conductingengagement with the stationary contact, means for holding the togglemechanism in a predetermined thrust transmitting position to maintainthe contacts in circuit closing position, and means for releasing theholding means; locking means movable from an initial position to anotherposition to prevent the release of the holding means from the toggleholding position and to a third position to hold the toggle mechanism ina different predetermined thrust transmitting position independently ofsaid holding means whereby to maintain the contacts in the circuitclosing position, said locking means comprising a reciprocably mountedmember biased for movement in one directionand adapted to be moved inthe opposite direction while the looking means is in the initialposition to efiect the release of the holding means.

8. In a locking mechanism for an automatic electric circuit breakerhaving relatively fixed and movable cooperating contacts, a toggle mechanism for moving the movable contact into ourrent-conducting engagementwith the fixed contact, means for holding the toggle mechanism in apredetermined thrust transmitting position to maintain the contacts incircuit closing position, and means for releasing the holding means;locking means movable from an initial position to another position toprevent the release of the holding means from the toggle holdingposition and to a third position to hold the toggle mechanism in adifferent predeterminedthrust transmitting position independently of theholding means whereby to maintain the contacts in the circuit closingposition.

9. In a locking mechanism for an automatic electric circuit breakerhaving a relatively stationary contact, a cooperating pivotallysupported contact, toggle mechanism for moving the cooperating contactinto current-conducting engagement with the stationary contact, apivoted latching member for holding the'toggle mechanism in a thrusttransmitting position to maintain the contacts in circuit closingposition, and electroresponsive means for releasing the latching member;locking means movable from an initial position to another position toprevent turning of the latching member from the toggle holding positionand to a third position to hold the toggle mechanism in a straighterthrust transmitting position independently of the hold ing means wherebyto maintain the contacts in the circuit closing position, said lockingmeans comprising a reciprocably mounted member biased for movement inone direction and adapted to be moved in the opposite direction whilethe locking means is in the initial position to eiTect the release ofthe latching member.

10. In a locking mechanism for an automatic electric circuit breakerhaving a relatively stationary contact, a cooperating pivotallysupported contact, a toggle mechanism for moving the cooperating contactinto current-conducting engagement with the stationary contact, apivoted latching member for holding the toggle mechanism in a thrusttransmitting position to maintain the contacts in circuit closingposition, and electroresponsive means for releasing the latching member;locking means movable from an initial position to another position toprevent turning of the latching member from the toggle holding positionand to a third position to hold the toggle mechanism in a straighterthrust transmitting position independently of the holding means wherebyto maintain the contacts in the 2;;

circuit closing position and to a position intermediate said initial andthird positions to pr vent a circuit closing operation of the contactswhile in the" circuit open position.

11. In a locking mechanism for an automatic electric circuit breakerhaving a relatively stationary contact, a cooperating pivotallysupported contact, a toggle mechanism for moving the cooperating contactinto current-conducting engagement with the stationary contact,a pivotedlatching member for holding the toggle mechanism in a predeterminedthrust transmitting position to maintain the contacts in circuit closingposition, and electroresponsive means for releasing the latching member;locking means movable i'rom an initial position to another position toprevent turning of the latching member from the toggle holding positionand to a third position to hold the toggle mechanism in a differentpredetermined thrust transmitting position independently of the holdingmeans whereby to maintain the contacts in the circuit closing positionand to a position intermediate said initial and third positions toprevent a circuit closing operation of the contacts while in the circuitopen position.

12. In a locking mechanism for an electric switch having relativelymovable cooperating contacts provided with actuating means for effectinga circuit closing movement of the contacts, together with means forholding the contacts in the circuit closing position, and means ellresponsive to the condition of the circuit through the contacts forreleasing the holding means; means for preventing a circuit openingmovement of the contacts by the releasing means and in consequence ofshocks comprising a member rotatable a predetermined amount in onedirection from an initial position to prevent the release of the holdingmeans and a further predetermined amount in the same direction toprevent rela tive movement of the contacts, said member beinglongitudinally movable in one direction while in said initial positionto effect the release of the holding means.

13. An electric switch comprising relatively movable cooperatingcontacts, collapsible actuating means for effecting the circuit closingoperation of said contacts comprising a toggle adapted to be released toeffect the circuit opening operation of said contacts, and means forpreventing the circuit closing operation of said contacts and thecircuit opening operation thereof both by said actuating means and byshock comprising a member adapted to be operated to a positionpositively to hold the joint of said toggle against movement when saidcontacts are in the open circuit position and to another positionpositively to hold the joint of said toggle against movement when thecontacts are in the circuit closing position.

14. An electric switch comprising relatively movable cooperatingcontacts, actuating means for effecting a circuit closing movement ofsaid contacts comprising acollapsible mechanism adapted to be operatedto effect a circuit opening operation of said contacts, and a movablemember adapted to be operated to one position to prevent the actuationof said mechanism when said contacts are in the closed circuit positionand to another position to prevent the actuation of said mechanism whenthe contacts are in the open circuit position.

15. An electric switch comprising relatively stationary and movablecooperating contacts, actuating means for moving said movable contactinto engagement with said relatively stationary contact comprising atoggle mechanism, and means operative on said toggle mechanismpositively to hold said movable contact against movement in consequenceof both shock and an attempt to operate said actuating means while themovable contact is in the open circuit position.

16. An electric switch comprising relatively stationary and movablecooperating contacts, actuating means for moving said movable contactinto engagement with said relatively stationary contact comprising atoggle mechanism adapted to be operated to effect the circuit openingmovement of said movable contact, and means operative on said togglemechanism positively to hold said movable contact against movement inconsequence of both shock and an attempt to operate said actuating meanswhile the movable contact is in the open circuit position and also whilethe movable contact is in the closed circuit position.

JAMES M. ANDERSON.

